Polar codes have been adopted as a channel coding scheme for the control channel of the 3rd Generation Partnership Project (3GPP) New Radio (NR) standards. In a downlink control channel referred to as Physical Downlink Control Channel (PDCCH) in the NR standards, a user equipment (UE) is configured with a time and frequency range (also referred to as search space) in which its valid control information may exist. The user equipment may perform decoding of received downlink signals within the search space to identify valid information, and in the process of decoding, errors may occur. These decoding errors waste the system resources and processing power, and hence, any reduction in the decoding processing can be of a great advantage.
The NR standards introduced distributed cyclic redundancy check (D-CRC) codes that exploits successive nature of a typical polar codes decoding scheme. Each D-CRC parity bit is used to validate a subset of information bits once they are decoded. If the D-CRC parity bit approves the corresponding information bits, the decoding process continues while if the D-CRC parity disapproves the corresponding information bits, the decoding process can be terminated early since a decoding failure is unavoidable in this case. Such decoding termination prior to decoding the entire information bits is referred to as early termination, and the order of the D-CRC bits as well as the corresponding set of information bits in a transmitted sequence of bits makes a difference in the early termination performance.